In known wiper blades, the purpose of the support element is to assure as uniform as possible a distribution of the wiper blade pressure against the window, which pressure is exerted by the wiper arm, over the entire wiping field wiped by the wiper blade. Through an appropriate curvature of the unloaded support element—i.e. when the wiper blade is not resting against the window—the ends of the wiper strip, which is placed completely against the window during operation of the wiper blade, are loaded toward the window by the support element, which is stretched in this state, even though the curvature radii of spherically curved vehicle windows change with each wiper blade position. The curvature of the wiper blade must therefore be somewhat sharper than the sharpest curvature measured within the wiping field on the window to be wiped. The support element consequently replaces the expensive support bracket structure with two spring strips disposed in the wiper strip, as is the practice in conventional wiper blades (DE-OS 15 05 357).
In a known wiper blade of the type known in the prior art (DE-OS 198 14 609). the support element ha two spring strips, which rest in receiving grooves disposed in the two longitudinal sides of a rubber-elastic wiper strip. This wiper strip has a top strip, which is essentially rectangular in cross section, with receiving grooves for the spring strips of the support element (FIG. 13), and has a strip-shaped wiper lip, which performs the wiping function on the window. The top strip and the wiper lip are of one piece and are connected to each other by means of an intermediary strip so that opposing walls of the top strip and the wiper lip are spaced apart from each other and constitute supports for the wiper lip, which is always disposed in a so-called drag position during the reciprocating wiper motion. In practice, it has turned out that under certain conditions, the flow conditions in front of the window reduce the pressure of the wiper blade against the window. A reduction of the wiper blade height in order to minimize this disadvantage can be achieved—as demonstrated by the known wiper blade shown in FIG. 12—by embodying the support element as a one-piece spring strip and attaching it, for example gluing it, to the top side of the top strip remote from the wiper lip. A glued connection of this kind can only adapt insufficiently to the harsh operating and environmental conditions—such as alternating stress, cold, heat, ozone influence, etc.,—for the wiper blade.